To accurately measure small pressure changes in a high pressure fluid system by means of a differential pressure transducer it is essential that the transducer provide accurate readings throughout the entire range of line pressures to which it may be exposed. Often, however, low range transducers suffer significant calibration shifts and changes in sensitivity at high average line pressures. Apparently, the increased stresses produced by high line pressures cause sufficient elastic strain in the transducer case to shift the relative positions of the sensing mechanism and the diaphragm or other deformable element in the transducer, resulting in a change of calibration.
Although this is a problem affecting the accuracy of laboratory tests conducted under conditions of high fluid pressures as well as the accuracy of differential pressure monitoring in a continuously operating commercial system, no practical solutions have been forthcoming.
It would be highly desirable, therefore, to have an effective accurate method for calibrating a low range differential pressure transducer at high line pressures which can be quickly carried out and which does not require the use of expensive equipment.